This invention relates to a method of driving an element by means of a liquid column. The invention also relates to an hydraulic impactor of the kind in which a piston surface of a driven member, for example a chisel, is loaded by means of a liquid column.
In U.S. Pat. No. 4,089,380 an hydraulic impactor is shown in which a hammer piston of steel impacts on an anvil with trapped liquid through which the impact energy is transmitted to a chisel. Although the liquid anvil permits a higher impact velocity of the hammer piston than the velocity that can be permitted if the hammer piston impacts directly on the chisel, the hammer piston is still heavy and thus, the entire impactor is heavy and large.
In U.S. Pat. No. 4,289,275 a cannon for shooting a liquid column is described which is invented by the same inventors as present invention. The cannon is intended for shooting the column into a pre-drilled blind hole in a rock boulder in order to split the boulder.
In U.S. Pat. No. 4,264,107 a demolition tool is shown in which a gas pressure accumulator is used to drive a tool through the medium of a liquid. The liquid and the tool accelerate together and the liquid does not impact on the tool.